Computer network administration often includes operations to maximize authorized access without generating excessive network traffic due to maintaining a record of users authorized to access a particular network resource and frequently updating the records. In simple cases, each resource maintains its own list of authorized users, and upon receiving a request for service checks the list to prevent security breaches due to access by unauthorized users. Users of a computer network are often organized into groups, which generally reduces the number of list entries that have to be checked by a resource (and updated by the system) prior to granting access to the resource.